1. Technical Field
The present invention relates in general to wireless communication and, in particular, to the utilization of access channels in a wireless communication network. Still more particularly, the present invention relates to a method and system for regulating autonomous messaging by subscriber units in a wireless communication network.
2. Description of the Related Art
In cellular telephone networks, one widely utilized communication technology is CDMA (Code Division Multiple Access). CDMA is a spread spectrum technology that distributes the signal of interest (e.g., a voice or data signal) over a wide radio frequency spectrum. CDMA can be implemented with any of a number of air interface standards, including the cellular IS-95A and IS-2000 standards and the PCS (Personal Communications Services) ANSI J-STD-008 standard. Each of these standards defines two groups of channels, the forward channel and the reverse channel.
The forward channel, which communicates voice and data from the cell to mobile stations, carries traffic, a pilot signal, and overhead information. The pilot and overhead channels establish system timing and station identity. The pilot channel also is employed as a signal strength reference in the handoff process, which transfers communication with a mobile station to another base station in the wireless communication network. The reverse channel, which communicates voice and data from the mobile station to the cell, carries both traffic and signaling. Any particular reverse channel is active only during calls or signaling by or to the associated mobile station.
In the reverse channel, the channels utilized for signaling, that is, carrying control messages, from the mobile stations to the cell are referred to generically as access channels. Some access channels are available for use by all mobile stations (i.e., are shared access channels), while some are dedicated for use by particular mobile stations. Examples of control messages carried by the access channels include Origination Messages that initiate calls, Page Response Messages that provide responses to pages, Registration Messages that provide information regarding the locations and identities of mobile stations, and Flash With Information Messages that alert the cell to changes in the hook states of mobiles.
In conventional CDMA networks, mobile stations have been permitted to send autonomous messages, which are defined herein as control messages originated by a mobile station that are not prompted by a specific request by the cell, via the shared access channels in an uncontrolled manner. This lack of regulation can lead to excessive autonomous messaging, for example, by a malfunctioning mobile station. Excessive autonomous messaging may also result from a poor choice of system parameters that require a mobile station to provide too many control messages, poor cell boundary planning that causes a mobile station to repeatedly re-register with a base station as the mobile user traverses the cell boundary, or simply user error. Excessive autonomous messaging can consume the limited bandwidth of shared access channels, resulting in mobile users experiencing access delays, access failures, or even service outages.
In view of the problems that may result from unregulated autonomous messaging, the present invention provides a method and system for regulating autonomous messaging by subscriber units (e.g., mobile stations) in a wireless communication network. A wireless communication network in accordance with the present invention generally includes a number of subscriber units, a base station controller, and a base station transceiver coupled to the base station controller. A parameter specifying an interval at which subscriber units in the wireless communication network are permitted to generate autonomous messages is stored, for example, in a system parameter database at the base station. The parameter is broadcast by the base station transceiver over-the-air to subscriber units in the wireless communication network. In response to receipt of the parameter, the subscriber units store the parameter and thereafter transmit autonomous message over-the-air only in accordance with the parameter. In one preferred embodiment, the parameter regulates how often autonomous messages can be transmitted by individual subscriber units. Alternatively or additionally, the parameter can be used to ensure that the subscriber unit is in a stable state before an autonomous message is transmitted by preventing transmission of autonomous messages while the subscriber unit is generating messages at too rapid of a rate.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.